This invention relates in general to remotely actuated tools for performing operations on subsea wellheads, and in particular to tools operated by hydraulic power.
A typical subsea well production system has a wellhead and a christmas tree installed thereon. A riser extends upward from the Christmas tree, and together with the tree and wellhead form a well bore. Various well components, such as a tubing hanger, a running tool, and a test tree, are positioned in the bore and must be actuated to perform their respective function. In conventional subsea well production systems, these components are hydraulically actuated through passages which extend upward within the bore to the surface. A fluid reservoir and a pump on the surface provide hydraulic pressure to the components.
Conventional systems require long hydraulic umbilical lines to span from the surface to the sea floor. The deeper the subsea well, the longer the umbilical lines must be, and the more flexure introduced into the hydraulic system as the lines flex from the stress of the hydraulic pressure. This flexure reduces the precision to which the components can be operated. Also, there is a great distance between the controlling pump and the component being actuated which increases response times to actuate the components. Finally, the fluid in the long umbilical lines must traverse a large distance and as such are easily contaminated.
Therefore, there is a need for a hydraulic actuation system that absolves the need for transmission of hydraulic fluid through long umbilical lines and minimizes the volume of fluid to provide fast, precise, and clean actuation of various well components.
The present invention presents a subsea apparatus for performing a task on a subsea wellhead assembly located adjacent to a sea floor. The wellhead assembly has a riser extending to a platform at a surface of the sea. The apparatus has a first hydraulically actuated component adapted to be lowered from the platform through the riser into engagement with the subsea wellhead assembly for performing a task on the subsea wellhead assembly. The apparatus has reservoir containing a fluid and the reservoir is carried by the first component. An electrically powered pump is carried by the first component for pumping fluid from the reservoir to the first component to actuate the first component. An electrically actuable controller is carried by the first component for receiving remote signals from the platform and electrically operating the pump.
A second hydraulically actuable component is adapted to be lowered from the platform through the riser simultaneously with the first component. A plurality of valves are interconnected between the pump and the first and second components. The controller is adapted to receive remote signals from the platform to actuate the valves and route fluid from the pump selectively to the components.
The first component is adapted to be lowered through the riser on a string of conduit. A power line to the pump is adapted to be carried by the string of conduit. A sensor is carried by the first component for sensing actuation of the first component and signaling the controller. A tubular joint is carried by the first component and the fluid reservoir, pump, and controller are mounted to the joint. The reservoir and the pump are positioned in close proximity to the first component. The first component may be part of a running tool for installing a string of tubing within the subsea wellhead assembly.
The present invention also presents a subsea apparatus for performing a task to a subsea wellhead assembly located adjacent to a sea floor. The wellhead assembly has a riser extending to a platform at a surface of the sea. The apparatus has a hydraulically actuable running tool adapted to be lowered through the riser and into engagement with the subsea wellhead assembly for installing a string of tubing within the subsea wellhead assembly. A reservoir is carried by the running tool for containing fluid. An electrically powered pump is carried by the running tool for pumping fluid from the reservoir to the running tool to actuate the running tool. An electrically actuable controller is carried by the running tool for receiving remote signals from the platform and electrically operating the pump.
A second hydraulically actuable component is adapted to be lowered from the platform through a riser simultaneously with the running tool. A plurality of valves are interconnected between the pump and the running tool and the second component. The controller is adapted to receive remote signals from the platform to actuate the valves and route fluid from the pump selectively to the running tool and second component. The second component may be a test tree valve or a latch for disconnecting a running string from at least a portion of the running tool while the running tool is in engagement with the subsea wellhead assembly.
A sensor is carried by the running tool for sensing actuation of the running tool and signaling the controller. A tubular joint is carried by the running tool and the fluid reservoir, pump, and controller are mounted to the joint.
In addition to the second component, the apparatus may have a latch for disconnecting a running string from at least a portion of the running tool while the running tool is in engagement with the subsea wellhead assembly. Here, the plurality of valves is interconnected between the running tool, second component, and latch such that the controller can actuate the valves and route fluid from the pump selectively to the running tool, second component, and latch. Here also, the second component may be a test tree valve.
The present invention also presents a method from performing a task on a subsea wellhead assembly located adjacent to a sea floor. The wellhead assembly has a riser extending to a platform at a surface of the sea. The method includes the step of providing a first hydraulically actuable component having a reservoir containing a fluid, an electrically powered pump, and an electrically actuable controller carried by the first component. The component is lowered through the riser into engagement with the subsea wellhead assembly. The controller is signaled from the platform to actuate the pump and pump fluid from the reservoir to the first component to actuate the first component to perform a task on the subsea wellhead.
A second hydraulically actuable component is lowered simultaneously with the first component and the controller is signaled from the platform to actuate valves between the pump and the components to route fluid from the pump selectively to the components. The actuation of the first component is sensed and the controller is signaled. The first component may be part of a running tool for installing a string of tubing within the subsea wellhead assembly.
The present invention also presents a method for installing a string of tubing within a subsea wellhead assembly located adjacent to a sea floor and having a riser extending to a platform at a surface of the sea. The method includes the step of connecting the tubing to a tubing hanger. A running tool having a fluid reservoir, an electrically powered pump, and an electrically actuable controller carried thereon is secured to the tubing hanger. A string of conduit is secured to the running tool and the tubing is lowered into the well and the running tool into the subsea wellhead assembly. The controller is signaled form the platform to actuate the pump thereby supplying hydraulic pressure to actuate the running tool to engage the wellhead assembly and set the tubing hanger.
A second component is secured to the running tool and lowered into the subsea wellhead assembly simultaneously with the running tool. The controller is signaled from the platform to activate valves between the pump and the running tool and second component to route fluid from the pump selectively to the running tool and the second component. The second component may be a test tree valve or a latch for disconnecting a running string from at least a portion of the running tool while the running tool is in engagement with the subsea wellhead assembly.